1. Field of the Invention
The present invention generally relates to optical disk apparatus and, more particularly, to an optical disk apparatus which is used to record and/or reproduce a color video signal or the like.
2. Description of the Prior Art
Conventionally, an optical disk apparatus is proposed to record and/or reproduce a color video signal and an audio signal by using an optical disk (see Japanese Patent Laid-Open Gazette No. 63-257395 and U.S. patent application Ser. No. 07/180,340).
In the existing optical disk apparatus, a color video signal and an audio signal can be recorded and/or reproduced during a period of time of 24 minutes by using a single side of an optical disk of 30 cm in diameter which is rotated at a constant angular velocity.
Incidentally, an optical disk apparatus which is exclusive for reproduction, i.e. so-called optical video disk player can reproduce the color video signal and the audio signal from the single side of the optical disk of 30 cm in diameter during a period of time of 30 minutes. Accordingly, the above-mentioned playback time, 24 minutes is shorter than the playback time of 30 minutes by 20%.
For this reason, the user utilizing both the above-mentioned recording and reproducing type apparatus and the apparatus exclusive for playback suffers from great disadvantage and this causes a serious problem to the user in use because the playback times are different though the operation procedures are the same.
Incidentally, in the above-mentioned recording and reproducing type optical disk apparatus, the innermost track of the optical disk in which the recording and reproduction are performed is defined from the position of the radius of 70 mm. This standard is made in order to keep the quality of the reproduced picture higher than the predetermined image quality.